1. Field of the Invention
The present invention relates to a sheet bonding method, a sheet bonding device, and a transfusion bag, and particularly relates to a technology for substituting air in a sealed space with desired gas (for example, inert gas) when bonding a functional sheet to a periphery portion of a bag main body filled with a transfusion by sealing these with each other.
2. Description of the Related Art
In general, a liquid medicine, a powder medicine, food, powder (sugar or the like), which is sensitive to humidity, an inspection chip, which detects specific gas, and the like are packaged in a package (packaging container). As a kind of such a package, for example, a transfusion bag filled with a transfusion containing sugar, an electrolyte, amino acids, vitamins, or the like is well known. A transfusion bag in which a resin film (plastic film) is made in a bag shape has been used in view of good handling properties, being lightweight, reduction in volume of waste, or the like.
The resin film, which is used as the material of a bag main body directly touching a liquid medicine in the bag-like body constituting this transfusion bag, has a low function such as gas barrier properties. This is because an additive which improves gas barrier properties of the film or the like is not used in order to prevent elution of such an additive in the transfusion.
However, it is easy for the liquid medicine, such as sugar, amino acids, or an electrolyte, with which the transfusion bag is filled, to significantly deteriorate due to oxygen. Therefore, if the bag main body is left to stand in the air, the liquid medicine deteriorates due to oxygen in the air transmitted through the transfusion bag.
Therefore, the gas barrier properties are secured (for example, JP1999-56970A (JP-H11-56970A) and JP1999-348171A (JP-H11-348171A)) by constituting the transfusion bag after bonding two functional sheets, which have a function layer with high gas barrier properties, to both surfaces of the bag main body formed of a resin film or the like.
The bonding of functional sheets is performed by sealing the gas barrier sheets with the bag main body through thermal welding or the like of the periphery portion of the bag main body after making these overlap each other.
However, when bonding the gas barrier film to the bag main body, there is a problem in that air enters the sealed space between the bag main body and the gas barrier film and oxygen in the entering air transmits the bag main body, and therefore, the liquid medicine is deteriorated.
Here, the sealed space refers to a space of an inner portion of the sealed portion between the bag main body and the gas barrier film.
Accordingly, in a case of bonding the gas barrier film to the bag main body, it is necessary to substitute air, which has entered the sealed space between the bag main body and the gas barrier film, with desired gas, for example, inert gas, or to remove the air.
In this manner, the necessity of substituting the air in the sealed space with desired gas or removing the air is not limited to the transfusion bag, and the same applies to an inspection chip or a package, such as a container or a bag body made of a plastic film, of food which easily deteriorates due to oxygen or the like. In addition, the desired gas is not limited to inert gas, and may be gas which is harmless or harmful to a substance packaged in a package.
In the related art, as a gas substitution method for substituting air in a sealed space with gas, there are, for example, JP2011-73715A and JP2004-323066A. This method is a method for sealing an opening of the sealed space through thermal welding or the like after inserting a gas nozzle into the sealed space, purging gas in the sealed space, and pulling the gas nozzle.
In addition, as the deaerating method for removing air in a sealed space, there is, for example, JP2010-76803A. This method is a method for sealing an opening through thermal welding or the like by removing air in a sealed space within a vacuum chamber for vacuum packaging after preparing the vacuum chamber.